Budget 4ac Mods

[Water Boy]

Copied a list of ideas from the old forum.

I know the 4ac is a pretty basic and low powered engine but for many it is the start for many hill sessions :thumbup:


Get someone to cut a new slot in the cam gear so that its held in a 5 degrees advanced position. This for me made me lose about 0.5 to 1L to 100km however I had a reasonable power gain between 3000 and 4000rpm.

Other than that a free flowing carb will probably be the best bang for buck



Advance the timing, run 98, flip the air filter lid upside down and bolt it on again, 2 inch exhaust with at least one baffled muffler.

replace the plugs, dizzy cap and rotor button.

Thats all thats really worth doing.


Head shave for some more compression, cam, carb, valve springs.


weber carby, straight through (or close to it) exhaust, 98 ron fuel, timing advanced all the way, remove clutch fan fit thermo.
also a button clutch makes those clutch kicks more potent.


elec dizzy, good plugs/leads, timing advance and 98

small exhaust, weber if youre rich

Hope that helps some newwer people to the Toyota side of things like myself! But as have most said if you are really keen save some extra dollars and go straigh for the 4age conversion.

[Sam-Q]

one I did: get an additional slot cut in the cam gear so it hold the cam in a 5 degrees advanced position. There will be a power gain beween 3000 and 4000 revs

[slide86]

lid flip FTW

[Dylan]

one of these
http://www.speco.com.au/images/AccAirSpeco.jpg

what about something like this
http://www.toyotapowered.com/index.php?showtopic=6

[shift_rook]

itb's on a 4ac seems like a bit of a waste to me

[R&D Mechanical]

on a 4ac i hope you mean

[ae86runna]

one of these
http://www.speco.com.au/images/AccAirSpeco.jpg

what about something like this
http://www.toyotapowered.com/index.php?showtopic=6

Change to mint elec dizzy with better plug-cables, put in one of those ^^, change to a better muffler and ur good to go with better mid-range response n fuel consumption.. havent tried better plugs tho..

[Driftspec]

Interesting to note that some 4ACs are better than others, depending on how they have been treated, etc. Eg. mine seems to run better with 95 at the moment, with 98 it seems to flood the motor, its a lot more peppy with it.

Also, pulling the snorkel out from the intake is a useful quick fix. Keeping it well serviced is also an important thing to do ;)

[Aezion]

my carby on the 4ac is dead, all it does is want to stall. my mate had this laying around said it would run alot better then the carby.
1977
hopfully get it on this week i got a couple days off :D

[Axentrik]

32/36 downdraft and redline filter.

http://img144.imageshack.us/img144/4850/engineafter.jpg (http://img144.imageshack.us/i/engineafter.jpg/) http://img144.imageshack.us/img144/engineafter.jpg/1/w600.png (http://g.imageshack.us/img144/engineafter.jpg/1/)

[Sprinter86]

you have a choice of:

motorbike filter(keep well oiled for the full 80kw gain)
http://www.ae86drivingclub.com.au/dcimages/9/4/7820.jpg

or
Custom Pod Bucket cold air intake!
http://www.ae86drivingclub.com.au/dcimages/9/4/7821.jpg
http://www.ae86drivingclub.com.au/dcimages/9/4/7822.jpg

[joeschmo_57]

shoot at the block with a 303. best mod if you want economy

theres cheap upgrades all over the place for these. lumpsttck for under $100 in some places

try club4ac.com

[vivioman]

you have a choice of:

motorbike filter(keep well oiled for the full 80kw gain)
http://www.ae86drivingclub.com.au/dcimages/9/4/7820.jpg


Got a larger photo of the above? I'm interested what was used as an adapter to the carby opening. :D

[Dylan]

^ as am i

[Sprinter86]

i dont have a bigger pic.....

it was actually made from steel tube by boky, it was originaly designed as a turbo pipe for a 4/3k turbo corolla we were going to build, but we gave up and it ended up on my daily sprinter haha.

heres a different angle

http://www.ae86drivingclub.com.au/dcimages/9/4/7825.jpg

[vivioman]

^^ very interesting. how is it held on to the carby opening though, by using hose clamps?

was the pcv hose disconnected?

[Sprinter86]

pcv is just open to the air haha no filter.

i removed the 4ac carbie thread thing that holds the factory filter on, and put a 3k on in (much longer) and then i bent it a little, so it actually uses the factory nut to hold the pipe on, hard to explain, so i drew a quick picture..

http://www.ae86drivingclub.com.au/dcimages/9/4/7826.jpg

[Dylan]

thanks

[rthy]

oh hai gais,

i bought a HKS performance filter kit for the 4AC
http://img26.imageshack.us/img26/766/dsc00373y.th.jpg (http://img26.imageshack.us/my.php?image=dsc00373y.jpg)

[vivioman]

pcv is just open to the air haha no filter.

i removed the 4ac carbie thread thing that holds the factory filter on, and put a 3k on in (much longer) and then i bent it a little, so it actually uses the factory nut to hold the pipe on, hard to explain, so i drew a quick picture..

http://www.ae86drivingclub.com.au/dcimages/9/4/7826.jpg

Very ingenious! :thumbup:

[Aezion]

^ yep i got a 32/36 DGA and redline air filter. dont know how much better it goes cuz i never drove the stock 4ac.

ill let you know how it goes once i get it on.
(Y)

[Dylan]

oh hai gais,

i bought a HKS performance filter kit for the 4AC
http://img26.imageshack.us/img26/766/dsc00373y.th.jpg (http://img26.imageshack.us/my.php?image=dsc00373y.jpg)


what size reducer have you used here?

Was this mod as effectice as your strutbrace with adjustable damper?

[rthy]

2" to 2.5" i think it was or something like that

and yes it was designed so when both the strutbrace and filter was installed it will increase the effectiveness of the stock adm brakes at 5000rpm

[Dylan]

thats sick man

[45aken]

Didnt dave from AJPS whip up a turbo 4ac back in the day?
something like stock manifold cut and a flange welded on, turbo carbie and a dodgey exhaust?
If i remember the thing ran for a fair while too.

[vivioman]

one of these
http://www.speco.com.au/images/AccAirSpeco.jpg

what about something like this
http://www.toyotapowered.com/index.php?showtopic=6

Where did you get one of those to fit a stock carby? I haven't seen one where the inner throat diameter was small enough to for the carby opening.

[Dylan]

This is the one you want, available from bursons and the like

9" diameter, 2" high
A9256 - 2 5/16" single barrel Stromberg

basically is for an old holden carb but its the same as the 4ac one aswell

http://www.speco.com.au/accair.html

[vivioman]

This is the one you want, available from bursons and the like

9" diameter, 2" high
A9256 - 2 5/16" single barrel Stromberg

basically is for an old holden carb but its the same as the 4ac one aswell

http://www.speco.com.au/accair.html

That's fantastic, thanks dude.

Any idea how much they would cost?

Have to plan a visit to Conventry's soon! :)

[Dylan]

roughly $40 from what i can remember

[ae86runna]

Sweeeett....

[KE_OBCT]

how far do people normally get with advancing the timing before motor pings? lol

[Dylan]

Depending on what fuel your running, 98 octane will be best. have heard some people running 20 - 30 degrees. Ive ran mine pretty high but didnt increase power greatly

[ae71]

i have 32/36 weber, redline filter and adaptor, elecronic dizzy, replaced cap and button. huge cam, removed/blocked off emmissons, ditched clutch fan for thermo, exhaust.. also replaced front main and cam seals but that doesnt effect performance.

still have to fit the adjustable cam gear, weber needs a rebuild, needs a new front pipe. oh and a good tune and it should be making another 10hp.

stock valve springs are fine, mine goes upto 7.5k not a problem with the springs.

motor is suffering a bit of blow by i think, may have to look for another fresh one or perhaps even a quick reco (rings, bearings, shave). would also be a good opportunity to fit the oil cooler.

[Sam-Q]

I ran straight LPG on my engine and I found I could advance the timing as much as I wanted it wouldnt ping only lose power.

[20v ae71]

I think mine has some sort of toyota diesel valve springs in it (just an old box of valve springs we had out the back) and i'm not exactly sure how hard it revs because the stock tacho just stops once you hit 8 grand. im thinkin maybe 8500rpm and then it starts to get valve float. but seriously anything over 7500 and you dont make anymore power, just sounds crazy lol.
The cam thats in there now makes max power at around 6.5 but i'd love to get something stupid made up just for the fun of it! I'm thinking along the lines of 292/292 duration, 9mm lift :D

actually... has anyone here got an old 4ac cam lying around?

[20v ae71]

oh and i'll chuck up a pic of my cold air intake tomorrow if I remember... much better than that $40 speco one and cost me like $15 from the wreckers

[vivioman]

oh and i'll chuck up a pic of my cold air intake tomorrow if I remember... much better than that $40 speco one and cost me like $15 from the wreckers

also detail how you made it fit, materials, etc.

thanks! :)

[20v ae71]

here they are.

pretty self explanitory, and i think they came off of hilux's or something. you could make up a plate so that the carby sealed on the adaptor bit but i wasn't running a filter anyway so yeah....
chuck a pod filter on if your picky :P

btw this isn't streeted hence the no filter bit

[viva]

whats that little air filter looking thing on top of the engine stickout sidw walds ? whats it do

[Dylan]

The airfilter assembly has been removed and replaced with that.Thats the factory air intake on some older cars. Looks to be off a old Hilux, Express van or similar

[Rice86]

i think the worse part about that is cutting a hole on the chassi...Yes you can use that hole in future i guess...but there are other things you can do to gain power without cutting up the car

[evil86]

example. drive it like you stole it:)

[DRFT]

i run mine lpg and it has equivalent to 110 octane fuel. pretty sweet lasts me a long time, i used to burn a can of oil every 3 weeks, but after using that moreys oil stabilizer stuff i havent burnt any oil and my car feels like the powers back. cheaper than a rebuild

[Sam-Q]

i run mine lpg and it has equivalent to 110 octane fuel. pretty sweet lasts me a long time, i used to burn a can of oil every 3 weeks, but after using that moreys oil stabilizer stuff i havent burnt any oil and my car feels like the powers back. cheaper than a rebuild

its actually around 100RON

[Touge Boy]

Unless you buy the straight propane from supagas. Modern LPG Runs heaps more butane than what it did a few years ago.

[Sam-Q]

thats true, there are also two other garbage gasses in there that bring the octane figure down.

[Dylan]

100% propane ftw, none of this butane stuff

[KE70]

Should be 50 50 mix with propane and butane but the key word here is should.

Propane = power
Butane = ecconomy

The other gases would probably for the smell.

[lovemy86]

the fastest mine ever went was on a tow truck.
only jokeing....well sort of. shaving the head works well.

[DRFT]

Should be 50 50 mix with propane and butane but the key word here is should.

Propane = power
Butane = ecconomy

The other gases would probably for the smell.

DONT confuse POWER with OCTANE, they are associated but different,

I believe that the gas im supplied with contains a mix of cfcs and nitrous oxides, just for the fun of it, thank you mobile

[MeZ Prod]

I have a 32/36 weber on my 4ac. Are there any guides on how to tune this beast?

[boxhead1990]

Someone mentioned quite an aggressive species cam back a bit I'm planning on poping my 4ac before swapping to a 4ag

So boost should be fun while my clutch and motor have a rather short life

I had a bloke at the cam place pretty excited to make me up the most angry cam he can think of

But I'd like to what I could pull valve springs from ???

[20v ae71]

Can't remember but I think I used 3sge possibly

[boxhead1990]

Cheers il look into it, I have a mate who's got a 3sgte in his 70 so I might ask him to measure up his springs and go from there then